Telephone system



Feb. 15, 1938. `w. G. PATTERSON ET AL. 2,108,140

vTELEPHONE SYSTEM 3 Sheets-Sheet l Flled Feb. 12, 1936 Fie. l.

Feb.' 15, 1938. W. G.- ISATTERSON ET AL 2,l08,40

TELEPHONE SYSTEM Filed Feb. 12, 193e 5 sheets-sheet 2 unumbc 54 tw Feb.15, 1938.

W. G. PATTERSON ET AL TELEPHONE SYSTEM Filed Feb. l2, 11936 5Sheets-*$11691I 3 rrr:

Patented Feb. 15, 1938 UNITED STATES PATENT OFFHCE TELEPHONE SYSTEM landApplication February 12, 1936, Serial No. 63,612 In Great Britain March18, 1935 18 Claims.

The present invention relates to automatic telephone systems and moreparticularly to systems employing register controllers,

In a multi-cnice area a subscribers designation comprises two portions,one portion including the digits representing the subscribers exchangeand the other portion the digits representing the number of his line atthat exchange. These portions for convenience will hereinafter bereferred to as code digits and numerical digits.

Systems are now well known in which the code digits are recorded inregisters and a translation of the digits into a routing designation iseffected, the translated code comprising one or more trains of impulses,not necessarily bearing any relation to the code dialled by a callingsubscriber, which are transmitted from a sending device under thecontrol of a control switch for the purpose of setting selectors toselect and set up a route to the Wanted exchange. The registers for thecode digits and the translating and sending arrangements are comprisedin a register controller which also includes registers for the numericaldigits, the numerical digits being transmitted under the control of thesame sending and controlling mechanism. Since the primary function ofthe register controller is to efiect the translation of the code digitsand the transmission of the translated code, it is held in use for alonger time than that necessitated by this function in order that thenumerical digits which have been stored so that dialling may proceedsmoothly during the time that translation and transmission of thetranslated code is taking place may be transmitted.

The object of the present invention is to reduce the holding time of theregister controller in a connection and so bring about a reduction inthe number of translating register controllers hitherto required in anexchange and to effect other economies.

In the present invention the numerical registers are separated from theregisters for recording the digits of that portion of the wantedsubscribers designation of which translation is required and the latterdigits are recorded on registers in a second circuit accessible from arst circuit, the second circuit including arrangements for translatingthe digits and controlling the transmission of the routing trains ofimpulses to which they have been translated. The first circuit includesregisters for the numerical por tion of a Wanted subscribers designationwhich are not required to be translated and sending and controllingarrangements for their transmission so that after the transmission ofthe routing trains has taken place the second circuit may be releasedand made free for use on another call. In a known system the translatingregisters are grouped, a group being associated with one or a pluralityof rst code digits which take effect on a selecting switch known as an Adigit selector which thereupon selects a free translating registercontroller in the group determined by the impulses received. Accordinglythe first circuit in the present invention may include an A digitselector and in what follows it will be assumed that this is the case.The second circuit then deals with the remaining code digits whichgenerally comprise two in number and are referred to as the BC digits.

The control of the output impulsing circuit is vested in the A digitselector circuit which accordingly includes the spring sets for thegeneration of impulses. This makes it convenient to include the impulseguard relay in the same circuit and the forced release arrangements mayalso be included in this circuit. As regards the routing trains, thecommencement and terminay tion of these is controlled over wipers of theA digit selector by signals, the output impulsing wires not being takenthrough to the second circuit, and a sending switch multiple between thetwo circuits being avoided. For the exercise of this control the secondor translating register controller circuit is provided with a sendingswitch adapted to be marked in accordance with settings of the BCswitch, the several markings being applied under the control of acontrol switch. The encountering of a marked contact by the sendingswitch brings about the operation of the stop relay in the A digitselector to terminate impulse transmission and a local stop relay may beprovided for the homing of the sending switch and the advancement oi thecontrol switch to apply a further marking to the sending switch or tosignal the end of routing train transmission. 'I'he stop relay may beheld until the sending switch has completed its rotation in the usualmanner.

The control switch may serve also as a digit distributor for theincoming BC digits, its stepping for this function being controlled bysteering arrangements in the A digit selector.

For the transmission of the numerical digits a sending switch andcontrol switch are provided in the A digit selector which operate in thesame manner as regards these functions as those norcuits. For thetransmission of the routing digits this sending switch may be steppedsynchronously and by the same impulsing contacts as the sending switchin the translating register controller circuit thereby serving toconnect the output impulsing springs into the output impulsing circuit,arrangements being provided to prevent the commencement of transmissionof a further train of impulses until both sending switches have reachedtheir home positions.

The control switch in the A digit selector may be stepped by theoperation of the stop relay to connect up in turn the several markingwipers of the numerical registers and since no circuits are required tobe completed by it until all the routing digits have been sent the earlycontacts in the control switch may be utilized for another purpose, forexample for providing, by means of connections over a local crossconnecting frame to the sending switch multiple, for the transmission ofone or more routing trains in connection with a single digit call whichmay be had Without engaging a translating register controller. Therelevant wiper of the A digit selector control switch would only beconnected up consequent on digit-cut-off action in the translatingregister controller or a simulated operation over a bank contact in thelevel or group to which the A digit selector is stepped by the singledigit. If the maximum number of routing trains is sent out consequent ontranslation in the register controller, the stepping of the A digitselector control switch after transmission of the last routing train mayitself bring about the connection of this wiper which may then bearranged to rest on contacts connected to the rst numerical register tobe connected up.

All the dialled impulses are preferably received on an impulse relay inthe A digit selector which repeats them to the several registersconcerned. The routing of the impulse trains to the several switches maybe effected under the control of a single steering relay which releasesto determine the end of an impulse. train and is thereupon re-operatedbefore the commencement of the next impulse train. The routing of therepeated impulse trains is conveniently effected by a distributingswitch stepped on the release of the steering relay and for this purposethe units register switch may be utilized. This would provide insuccessive positions for the routing of the A digit to the A digitselector stepping magnet, and then, over a wiper of the A digit selectorand a wiper of the control switch in the translating register controllercircuit for the BC digits to the two magnets of a two motion BC switch.'I'he numerical digits are then routed in turn to the numericalregisters. Two successive contact positions max7 be assigned to eachincoming digit and the steering relay may be connected t0 even contactsin one bank of the distributor the wiper of which is connected to afront contact of the impulse relay and to odd contacts in another bankof the distributor the wiper of which is connected to a back contact oithe impulse relay the distributor magnet being connected fordistribution purposes over seh" interrupting contacts to the evencontacts in the last mentioned bank and over the self-interruptingcontacts and a back contact of the steering relay to the odd contacts inthe rst mentioned bank.

The impulse relay may be operated on seizure of the A digit selector byone winding connected to the incoming test wire, arrangements beingprovided to disconnect this winding and provide an alternative holdingcircuit over the test wire consequent on the operation of the impulserelay, another winding of the relay being connected to the pulsingcircuit. The connection of the impulse relay to the test wire mayinclude a wiper and normal contact of one of the numerical registerswitches which is given a preliminary step on the operation of theimpulse relay.

The BC impulses and the steering impulses may be transmitted overdiierent wipers of the A digit selector and the translating registercontroller is engaged over a test wiper of the A digit selector in theusual manner. The marking circuit of the BC switch may extend back overa further wiper to the A digit selector circuit and another wiper mayprovide a circuit for the transmission of the signals to the stop relay.

In the A digit selector a release relay may be connected to a furtherwiper, the wire outgoing from its associated bank being cross connectedto the digit-cut-oi terminal on the translating frame. When operatedthis relay brings about the opening of the test wire and the release ofthe translating register controller. If no numerical trains are to betransmitted release may be brought about by opening the test wirecircuit .a

by the operation of a cut-oir relay in the translating registercontroller circuit. Under this condition, with the non-operation of therelease relay, a cut-off relay in the A digit selector may be operatedto bring about its release.

An embodiment of the invention will now be described by way of examplewith reference to the accompanying drawings.

In the drawings Figs. 1 and 2 show an A digit selector and numericalregisters on which are -v recorded the numerical portion of asubscribers designation together with the necessary control circuits andimpulse repeating arrangements. Fig. 3 shows the translating register onwhich are recorded the code. portion of a subscribers designation andcontrol circuits therefor. Relays and magnets performing like functionsare similarly designated in the two cases but for differentiation thedesignations of the relays and magnets in Fig. 3 have the letter Cadded.

In Figs. 1 and 2 the A digit selector ADS is of the two motion type andis provided with six wipers and contact banks and its movements arecontrolled by vertical magnet V, rotary magnet R, and release magnet Z.The outlets from levels last contact in the bank of wiper 4, and level Iis not used. The registers MS, CS, DS, US for the usual 4 numericaldigits of a subscribers designation are 25 point single motion reversedrive stepping switches, i. e. the switch wipers are advanced onretraction of the magnet armature, the magnets of which are designatedMM, CM, DM, and UM for the thousands, hundreds, tens and units digitsrespectively. The hundreds and tens registers have eachl three wipers,the units register has six wipers and the thousands register fourwipers. These are designated CSI- CSB, DSI-DS3, Usl-USE, and MSl--MSArespectively. SM is the magnet of the sending switch SS which isprovided with ve Wipers designated SS-SSS, and which operates todetermine the number oi impulses to be sent out in each numerical train.CNM is the magnet of the control switch CNS which eects the connectingup of the several registers in turn for the sending of impulsesindicative of the subscribers local number or of a set of terminalsespecially provided for manual board calls and is provided with fourwipers designated CNSI CNSQ. The units register is also employed as adigit distributor for routing the incoming dialled digits to the severalregisters in turn. With the exception or" switches US and SS theseswitches have two normal positions one at the end of the bank inposition i of their wipers and the other in position i3. Of the r-elaysshown A is the impulse relay which responds to impulses received overthe pulse wire pu, B and BA are slow releasing release relays, C is theslow releasing dialling relay which is controlled over wipers US! andUSil of the units register and is pre-operated for each train ofimpulses, D is a shunt eld relay connected to the positive and negativewires over which loop impulses are transmitted for setting the selectingswitches in the several exchanges concerned, G is a stepping relay whichby interaction with magnet R produces the hunting action of the A digitselector and H is the test relay. 1G is the usual impulse guard relayprovided in register controllers, SZ is the stop relay which determinesthe end oi an output impulsing train and CO is the cut-ofi relay whichis operated after the last impulse train has been sent to release the Adigit selector circuit. To and M are time pulse relays for bringingabout a forced release of the selector in certain circumstances. DC is arelay which is operated to bring about the connection oi the numericalregisters to the control switch. Contacts SI, s2, s3, and sil areoperated mechanically when the selector is stepped onto the lastcontacts in a level, nl, n2 and n3 are contacts operated when theselector makes its iirst vertical step. Contacts mmm, 8mm and so on areself interrupting contacts operated by the magnets MM, SM and so on andcontact rl is a contact operated by rotary magnet R towards the end ofits stroke. A spark quenching circuit consisting of a resistance andcondenser in series is shunted across each magnet and the battery. Thesecircuits are not shown in the drawings but their use is well known.Impulses for stepping the sender switch SS and the sender switch SSC inFig. 3 are generated by the impulsing springs Ii and loop impulses forthe setting ci selecting switches are generated by the springs l2.

In Fig. 3 the switch which receives the second and third code digits andwhich is commonly known as the BC switch is a two motion selectordesignated BCS with 6 wipers and contact banks designated l-E. Itsmagnets are designated VC, RC and ZC, and contacts ncl, no2, no3 arevertical oir-normal contacts operated when the switch takes its rstvertical step. SMC is the sender switch. magnet, the wipers of thisswitch being SSCl-Z. CNMC is the magnet of the control switch CNSC ofwhich the wipers are designated CNSCl-S. This latter switch has normalcontacts in wiper positions i and i3. Relays BC, SZC, COC correspond torelays B, SZ and CO in Figs. l and 2. The sending and control switchesare also J-point reverse drive switches.

The general operation or" the circuits shown is as follows. impulses arereceived by relay A and are repeated in turn to the vertical magnet V,vertical magnet VC, rotary magnet RC and the register magnets MM, CM, DMand UM, register US acting as a distributor for the routing or" theimpulse trains under the control of relay C which is operated before thecommencement of each impulse train. In response to the first impulsetrain, the A digit selector is stepped to a level in accordance with thenumber of impulses in the train and then hunts in that level in searchof a free translating register. The second impulse train steps the BCswitch vertically and the third train steps the wipers of the BC switchround the selected level, switch CNSC operated over wiper of ADS actingas a digit distributor. The remaining impulse trains are repeated byrelay A to the numerical registers which are connected up in turn byregister US. After the third and last code digit has been received andrepeated, sending commences, both sending switches being operated inparallel, springs I2 being connected in the output impulsing loop overwiper SS2. When the contact of the sending switch SSC marked over therst wiper of the BC switch is encountered by wiper SSCZ, relay SZCoperates and a signal is transmitted over wiper 2 of ADS to operaterelay SZ to terminate impulse transmission. Both sending switches nowhome and switch SSC commences to search for the marking applied overWiper of switch BC, this wiper being now connected up consequent on astep having been taken by switch CNSC when the sending switches arestepped to their normal contacts. Relays SZ and SZC are held in parallelover wiper 2 of ADS and wipers SSI and SSCI. This action continues untilall the routing trains have been sent out whereupon a circuit is thencompleted over a wiper of the BC switch and terminal dc to operate relayDC. This relay brings about the release of the register controller andthe self-stepping of switch CNS to a position in which the thousandsregister is connected up. Transmission of the stored numerical digitsthen takes place in the usual manner. After the last impulse train hasbeen sent, relay CO operates to release the A digit selector.

Ii the call is to a manual board position the A digit selector will bestepped to its 10th level and rotate to the last contacts in that level.Relay DC will be operated but since contacts s are operated no automaticadvance circuit for the switch CNS will be provided but it will bestepped as a controller under the influence of relay SZ. The sendingswitch SS is started and proceeds to hunt for markings applied over asmall cross connection frame CF and wiper CNSB, over the rst andsuccessive contacts in the bank of this wiper. Up to ve routing trainsmay be had for the routing of a call to a manual board position.

If the call does not require the transmission of any numerical impulsetrains as in the case of special service calls obtained by dialling TEL,TOL or TRU, both circuits are released as soon as the last routing trainhas been transmitted.

A detailed description of the operations in'- volved in setting up acall will now be given, when subordinate features of the invention willbecome apparent.

On the initiation of a call the calling line is extended to a rst codeselector having a relay group which brings about the operation of ahunting switch to search for and extend the line to a iree A digitselector. It will be assumed that the A digit selector shown in Figs. 1and 2 is free and is seized by the hunting switch. The selector ismarked free by reason of battery potential on wire p and the huntingswitch tests in to this battery over wire p, key contacts KB, contactsco3, n2, resistance to battery and in parallel therewith over wiperMSfl, contact l, lefthand winding of relay A to battery and in paralleltherewith over the right hand polarizing winding of shunt field relay Dto battery. Relay A operates over wire p and when the pulse wire pu isswitched through in the rst code selector relay group, relay A is alsoenergized in its righthand Winding over wire pu. Contact a2 closes acircuit for relay B which operates and at contact b5 closes an operatingcircuit for relay BA. Contact bI closes a point in an impulse repeatingcircuit to the several register magnets, contacts b2 and bB close pointsin an eventual holding circuit for relay C over wiper USI, contact b3prepares a circuit for holding the A digit selector over wiper MS4 andwire p and contact b4 prepares a connection for a general holding earth.Relay BA having operated, contact bal connects battery to the lastcontacts in all levels in the bank of wiper 3, contact ba2 closes acircuit from earth over contact aI, wiper US4 in position I, Wiper MS2in position I, commoned off-normal contacts in the bank of wiper MSI,contacts mmm, magnet MM to battery in which magnet MM operates, contactba3 opens a point in the homing circuits for the several numericalregisters and contact M4 prepares a circuit for the time pulse relay TP.Magnet MM operates and by interrupting its own circuit at contact mmmsteps switch MS to position 2. In this position a circuit is completedfrom earth over contact al, wiper USA, contact be2, wiper MS2, contactumm, magnet UM to battery and the magnet operates and by interruption ofits own circuit at contact umm steps switch US to position 2. Thecircuit for the left-hand winding of relay A is now interrupted at wiperMS4 and the relay is left dependent on its right-hand winding. Batteryover a resistance is now connected over wiper MSII and the commonedofi-normal contacts, contacts b3, co3, key contacts KB to wire p. Thestepping of switch US has disconnected earth from wiper MS2 andconnected it over unoperated Vertical oir-normal contacts nl of theswitch ADS and contacts s3 to relay C. Relay C operates and at contactcI disconnects itself from the commoned odd contacts in the bank ofwiper USii and at contact c2 disconnects itself from the commoned evencontacts in the bank of wiper USI. Contact c3 prepares a holding circuitfor relay C over wiper USI, contact c4 connects dialling tone over wireDT to wire fr which at this time is connected over a condenser to one ofthe incoming speaking wires in the first code selector. Contact c5prepares a holding circuit for relay TP and contact c6 prepares theimpulse repeating circuit which in position 2 of switch US extends overwiper USS to vertical magnet V of switch ADS.

The circuit is now in a condition to accept dialled impulses which arereceived over wire ma on relay A. Relay A at contact CL2 repeats theimpulses of the rst impulse train over the above traced circuit tomagnet V which responds and steps the switch ADS vertically. During thebreak periods of the impulses, relay C is held by earth over backcontact ai contacts c3, b2, wiper USI in position 2 for the firstimpulse train and in a subsequent odd position for later trains, andcontact h6. At the rst Vertical step of the switch the vertical onnormal contacts are operated and Contact nl disconnects relay C fromcontact 2 in the bank of wiper USL It may here be noted that contacts upare normal post springs which are changed over when the wipers ci switchADS are opposite the rst level of contacts but which are restored whenthe wipers are stepped to the second level. At the end of the rst trainof impulses relay A remains steadily operated, and contacts aI and nlbeing in` their front positions relay C releases and disconnectsdialling tone at contact cti. Contacts cI and c2 close the followingcircuit; earth over contact ai, wiper US4 in position 2, contacts ni,cI, npi, c2, umm, magnet UM to battery. Magnet UM operates and byopening its contacts umm steps the units register to position 3. In thisposition a circuit is closed from earth over contacts n3, bLi, wiperUS2, contact gI magnet R to battery. Magnet R operates and the switchhunts for a free outlet to a translating register. The test for a ireeoutlet is battery on the contact in the bank oi wiper t and in the caseof a free translating register this will be found over contacts KBC,coc, 1203 and relay BC and in parallel therewith contact bcl and aresistance. The test circuit is then from this battery over wip-erright-hand low resistance winding and higher resistance left-handwinding of relay I-I, contact dc, wiper USZ to earth over contacts bland n3. The test wires of busy outlets will be at substantially earthpotential applied over the low resistance winding or" the test relay ofthe selector engaging it. When a busy outlet is encountered by switchADS, relay G operates in a circuit from the busying earth over wiper 3,right-hand winding oi relay I-I, contacts hl and TI. Relay H does notoperate in this circuit.

Contact y! opens the circuit of magnet R which in turn opens the circuitoi relay G. The magnet releases and on the release oi relay Gre-operates, steps the switch wipers to the next contacts and closesagain the circuit for relay G. When a free outlet is encountered,battery potential will be present on the junction point of Contact hIand relay H so that relay G is shunted and does not operate and magnet Rcontinues energized. Relay H is operated over its two windings inseries. Contact hi disconnects relay G and closes a holding circuit forrelay I-I over its low resistance right-hand winding, contacts cZcI, biland n3, independently of switch US, and Contact h6 closes a steppingcircuit for magnet UM. This extends from earth over contact ai, wiperUSt, contacts h, c2 and umm and the units register is stepped toposition Il in which the circuit of magnet R is opened at wiper USE.Contact h2 prepares to extend earth over wiper US2 to wiper I of ADS,contact h3 connects relay SZ to wiper 2, contact hf connects relay DC towiper 13, contact h5 prepares the impulsing circuit over wiper 5 for themagnets oi the BC switch, contact L'I opens a point in a short circuitpath about contact m2 in the connection ci the negative wire to relay Dand contact h disconnects the dialling tone circuit. In position ofwiper USi a circuit is closed for relay C and this relay operates andprepares the impulsing circuit as before. In the meantime relay BC (Fig.3) has operated in the test circuit and locked itself to the test wireover contact bci and contact bell has opened the homing circuit forswitch. CNSC.

The first impulse of the second train is received by relay A andrepeated over wiper USt in position 4i, contact wiper 5, wiper CNSC2 inposition i to magnet VC. At the same time magnet UM is energized in aself stepping circuit over the back contact ai and wiper USt and switchUS is stepped to position 5. Contacts l to 'I in the bank of wiper US5are connected together and the wiper is a bridging wiper so that nointerference with impulsing takes place. Succeeding impulses or thesecond train are repeated over wiper USS in position 5. In this positionoi switch US a holding circuit during impulsing for relay C is completedover wiper USI, and over wiper US2 earth is extended over wiper G tomagnet CNMC which is thereby operated. At the end of the impulse trainrelay C releases as in the case of the rst impulse train and closes astepping circuit over wiper USG and contact c2 to magnet UM and switchUS is stepped to position 6 in which the operating circuit for relay Cis again closed. In position 53 of wiper USE the circuit ci magnet CNMCis opened and the switch CNSC is stepped to position 2 in which magnetRC is connected in place of magnet VC in the bank of wiper CNSC?. Thethird impulse train is repeated to magnet RC inA positions 6 and 'i ofswitch US and magnet CNMC is energized as before to step switch CNSC atthe end of the train to the third position. Relay C releases at the endof the train and switch US is stepped to position S in which relay C isreoperated. The fourth impulse train is repeated over wiper USt` inpositions 8 and 9 to magnet MM of the thousands numerical digit registerand the ith and sixth impulse trains are similarly re peated oversuccessive pairs of contacts in the bank oi wiper USG to magnets CM andDM. Switch US is therefore stepped from position i3 to position I 4 atthe end of the sixth impulse train and contacts I4 to 23 are commonedand connected to magnet UM which is impulsed over this circuit to setthe register in accordance with the units digit.

In positions S to ifi oi switch US earth is applied over wiper US?,contact .b2 and wiper i to wiper CNSC3 to provide for the operation ofrelay SZC. After wiper USt leaves position Iii the operating circuit ofrelay C is disconnected so that the relay releases at the end of theseventh impulse train and is not re-operated. When switch US has steppedfrom position I, magnet CNMC reieases and steps switch CNSC to its 3rdposition in which wiper l of switch BCS is connected to earth over wiperCNSC3. In position 8 and successive positions or" switch US earth isconnected to relay IG in the following circuit; earth over contacts n3,bi, mi, wiper USE, contact I, in the bank of wiper CNSA, contacts di,323, and co2, Vhen springs Il open, relay IG operates and disconnects atcontact igi the short-circuit imposed oy the closure of impulsingsprings Ii and connects these springs in a circuit for magnet SM.Contact ig/2 opens the homing circuit for switch SS, contact z'g3substantiates contact di and contact gli extends the circuit overimpnlsing springs II and contact h to wiper 5 thence over wiper CNSC? tomagnet SMC. Magnets SM and SMC are thereby stepped in synchronism andwhen wiper SSZ reaches position 3 the output impulsing loop which wasprevi.- ously closed over the winding of rel-ay D has springs I2included in it, the winding of relay D being short-circuited over wiperSS2. Springs Ii and I2 are arranged so that when one opens the othercloses. When therefore, magnet SM is energized the loop is opened andthe de-energization of the magnet steps the sending switch and when thisreaches the next contacts the loop is closed over springs I2. Impulsingcontinues until wiper SSC2 reaches the contact marked over wiper I ofswitch BCS whereupon a circuit is completed for relay SZC from earthover contacts n3, b4, ml, wiper US2, contact h2, wiper i of ADS, CNSC3and wiper l of BCS, the cross connection to the bank of wiper SSCZ,wiper SSC2, relay SZC to battery. A circuit in parallel with relay SZCis closed over wiper 2 of ADS, contacts h3 and s2 for relay SZ. Boththese relays operate and lock up over their respective contacts i andwipers I oi the sending switches. Contact seri short circuits springs IZto prevent further impulses being transmitted over the loop, contact S23opens the circuit ior relay IG and the stepping circuit for magnet SM,contact seti opens the stepping circuit for magnet SMC, contact S25closes a circuit over contact ma for magnet CNM which steps switch CNSon the release oi relay SZ, and contact S25 closes a homing circuit overwiper SS4 in positions SI5-i8 and impulsing springs II, for magnet SM tohome the sending switch. Contact szc closes the homing circuit formagnet SMC and contact sa connects earth to operate magnet CNMC. It willbe seen that the holding earth for relays SZ and SZC passes over wipersSSCI and SSI in parallel so that both relays are held until the twoswitches vhave reached their home position. Switch drives to position I5in a circuit over contacts g2 and Smm and from I5 it is stepped toposition I9 by impulsing spring II over contact set, the former drivingcircuit being again completed in positions dBi-25. When both switcheshave reached normal, magnet CNMC releases and wiper 2 of switch BCSbecomes connected up in place of wiper I.

Successive trains oi impulses are transmitted in the same manner inaccordance with the cross connections between the bank of wiper' SSC2and the several contacts marked over successively connected wipers ofswitch BCS, switches CNS and CNSC being stepped after the completion ofeach train, until, the requisite routing trains having been transmitted,a wiper oi switch BCS set to a contact strapped to terminal dc isencountered. Thereupon earth over wiper CNSC3 is extended over therelevant BCS wiper, terminal dc, wiper i of switch ADS, contact h4 torelay DC. Ii six routing trains are to be transmitted there will be nocross connection between switch BCS and terminal do but the stepping ofswitch CNS to position 'i closes a circuit from earth over wiper CNS2for relay DC. Relay DC operates and locks up over contacts del, b4, andn3 and opens the holding circuit of relay H and at Contact dc opens theoperating circuit of relay I-I. Relay H releases and a circuit is nowcompleted from earth over contacts n3, b4, dc2, h, ded, to wiperl CNSS.At contact dc a self drive circuit for switch CNS is closed as followsif less than 6 routing trains have been sent out: earth over wiper CNSE,commoned contacts i! to contacts dos, si, and cnmm and switch CNS isdriven to position i in which wiper CNS3 rests on the contact connectedto wiper MSS of the thousands digit register. Contact dat opens theshort circuit about contact m2 against the closure of contact h'i andcontact do? opens a further point in the dialling tone circuit.

The release of relay H disconnects earth from wiper 3 of ADS and relayBC releases. Contact bei opens the test circuit to guard against seizureoi' the translating register until all the switches have homed whereuponcontact no3 becomes closed, contact be2 completes a homing circuit forswitch SSC over wiper SSCE and contact smcm, contact bc3 operates relayCOC and contact bcii prepares the homing circuit for switch CNSC to becompleted when switch SSC reaches its home position. Inits home positionWiper CNSCi completes a circuit for release magnet ZC of the BC switch.The BC switch is released and when it is fully restored contacts nc arerestored,

l contact nel opening the circuit of magnet ZC,

contact no2 opening the circuit of relay COC and contact no3 re-closinga point in the test-in circuit. Relay COC performs no useful function inthis type of call and its release re-closes the testin circuit atcontact coc2.

By the time the routing trains have been transmitted the hundreds digitwill probably have been received and stored in register CS. When,therefore, wiper CNSd is stepped to its seventh contact earth overwipers CS2 and CNS4 will be applied to relay IG and the transmission ofthe thousands digit will commence. Switch SS will be stepped untilwiper' SSS encounters the contact marked over wipers MS3 and CNS3,impulses being transmitted over the loop at each step of the switch asbefore described until relay SZ operates in the marking circuit justreferred to. On the operation of relay SZ the relay lo-cks up overcontact sai, and at contact S24 short circuits the impulsing springs I2,at contact sa releases relay IG and opens the impulsing circuit formagnet SM and at contact sa5 energizes magnet CNM. The sending switchhomes and releases relay SZ. Magnet CNM thereupon de-energizes and stepsswitch CNS to position 8 in which wiper CS3 is connected up in place ofwiper MS3. The hundreds digit is transmitted, followed by the tens andunits digits in a similar manner, switch CNS being stepped one contactafter the transmission of each digit. When wiper CNS3 is stepped ontoits eleventh contact after the transmission of the units digit, earth isapplied thereover to the right hand winding of relay CO and this relayoperates and locks up over its contact col. Contact co2 opens a point inthe circuit for relay IG and contact co3 opens a point in the circuitover wire p. This latter operation results in the release of a. relay inthe iirst code selector relay group which opens the circuit over wire puand disconnects the remaining wires which lead to the A digit selector.Relay A releases and releases relay B which in turn releases relay BA.The restoration of contact b4 closes a holding circuit over contact d2for the left-hand winding of relay CO, relay CO being of the slowreleasing type. Contact b4 also releases relay DC. Contact ba3 onclosing completes a circuit as follows: earth over wiper SSL! when thisswitch has reached its home position, contact ba3, wiper CNSI in anoffnormial position, contacts cnmm, magnet CNM to battery. Switch CNS ishomed by the self driving of magnet CNM in the above traced circuit andwhen the home position` is reached wiper CNSI extends earth over wiperDSI to magnet DM and switch DS is homed. Switches CS and MS are homed ina similar manner whereupon earth is extended over wiper MSI, contact b2,wiper USI, contacts umm, to magnet UM and the switch US is homed. In itshome position earth is extended over wiper USI and contact co4 to therelease magnet Z of the switch ADS and that switch is released andrestored to normal. Contact nl re-closes a point in the initialoperating circuit for relay C, contact n2 closes a point in the test-incircuit over wire p and contact n3 releases relay CO. Contact co3 closesa further point in the test-in circuit to make the circuit available forfurther use and contact co4 opens the circuit of magnet Z. All theapparatus in the A digit selector is now in its normal condition andready for further use.

The above described operations are those which take place for a call toa subscriber connected to an automatic exchange and in which nocongestion is encountered.

If the A digit selector is unable to nd a free outlet to a translatingregister, the wipers are stepped round the level to the last contactswhere they are stopped by the operation of relay H from batteryconnected over Contact bal and wiper 3. As the wipers are stepped tothese contacts, contacts sl, s2, s3 and s4 are operated. Contact s!opens the stepping circuit over wiper CNSZ for switch CNS contact s2disconnects wiper 2 of ADS from relay SZ and applies a busy signal overwire BS, last contacts in levels 2--9,wiper2 of ADS, contacts h3 and s2and wire fr to the first code selector relay group from which it isrepeated over the calling line. Switch US is stepped from position 3 to.position 4 on the operation of relay H but relay C is not re-operated ascontact s3 is now open. Any further impulses received are not repeatedas contact c6 is open and the selector circuit remains in the conditionit now assumes until the subscriber clears whereupon the release ofrelays A, B and BA in succession brings about the release of relay H andthe operation of relay CO over its left hand winding and the circuitsare thereupon restored in the manner previously described.

If a call is made to a manual position by dialling the single digit 0the A digit selector is stepped to its 10th level over which the wipersrotate to the last contacts. Contacts s are operated as before but abusy signal is not transmitted as wire BS is not connected to the lastcontacts in the 10th level. In position 4 of wiper US2 earth is extendedover the last contact of the 10th level in the bank of wiper 4 andcontact h4 to relay DC. Relay DC operates and releases relay H and earthis extended over contact dc2 and wiper CNSII to relay IG and magnet SMand sending starts. The sending switch multiple is marked over the smallcross connecting frame CF and wiper CNS3, contacts dell, h2, dc2, b4 and113A and when the contact marked is reached by the sending switch, relaySZ operates with the results before described and at contact S25 stepsswitch CNS to position 2 in which a further Contact is marked for thetransmission of another routing train. The self-stepping circuit forswitch CNS is open at contact sI. Markings are applied to contacts insending switch bank over wiper CNS3 in its successive positions until asmany trains of impulses as are required to route the call to the manualposition have been transmitted. When this has been done or when thewiper CNS3 is stepped to position 6 a connection is made over the wiperto terminal co whereupon relay CO is operated either by earth overterminal co or by earth over contact stl and the selector is released.

If a call is required to a subscriber connected to a manual exchangewith coder call indicator working, operations can take place as abovedescribed for setting up the route to the exchange until a junction tothe required manual exchange is. taken into use. A coder is associatedwith the junction at its outgoing end in which the numerical portion ofthe wanted subscribers designation is recorded and arrangements areprovided at the outgoing end of the junction whereby a current reversalover the line wires is effected which brings about the operation ofrelay D until a free coder is available and ready to receive the number.Contact dI opens the circuit for relay IG to hold up impulsetransmission until the coder is ready whereupon relay D is released andthe transmission of the output impulses proceeds in the normal manner.

If a call is made to a special service position such as may be had forexample by dialling TEL, TOL or TRU, no numerical digits are dialled andit therefore becomes necessary to release the A digit selector after thetransmission of the last routing train. When the last routing train hasbeen transmitted, the next wiper of the BC switch to be connected upwill be found resting on a contact connected to terminal coc. Earth overthis wiper and terminal coc operates relay COC by means of its left handwinding. Contact coc2 releases relay BC and this relay on releasingcloses at contact bc3 a holding circuit for relay COC over its righthand winding and the translating register is released. Relay I-I (Fig.2) releases and the units register now being in position 8 a circuit iscompleted for relay CO from earth over contacts n3, b4, wiper USZ,contacts h2, ded, (relay DC has not been operated), righthand winding ofrelay CO to battery. Release of the A digit selector follows.

Attention may now briefly be given to the operations which take placeunder certain irregular conditions.

If a spare exchange code is dialled switches SSC and SS continue to stepas there will be no marking over the wipers of the BC switch. Whenswitch SS reaches position I4 a circuit will be closed over wiper CNS4and contacts m4, S23 and wiper SSE for relay M. Relay M operates andlocks up over contacts ml, b4 and n3 and earth is connected overcontacts n3, b4, c5 and m3 to wire fr which brings about the release ofthe A digit selector from the first code selector relay group.

If the digit 1 is dialled as one of the BC digits a similar operationtakes place while if this digit is dialled for the A digit the A digitselector is stepped to the rst level and springs np are operated. At theend of the impulse train relay C releases but the stepping circuit formagnet UM is now open at contact np and a circuit is closed over contactal, wiper US4 in position 2, contacts nl, cl and up for the releasemagnet Z. Magnet Z operates and releases the selector whereupon relay Cre-operates and the circuit is prepared for normal operation.

If no impulses are received within a predetermine-d time after the Adigit selector is taken into use or if a delay between the dialling ofconsecutive digits ensues, the following operations take place. Earth isconnected periodically to wire SP and the rst application after theoperation of relay BA and closure of contact ba4 operates relay TP overits left-hand winding. Relay TP locks up over its right hand winding andcontacts tpl and n3. After the elapse of a prescribed interval from theearthing of wire SP earth is applied to wire ZP. If relay TP has beenoperated and locked, relay M is now operated over its righthand winding,contact tpZ and wire ZP and the wire fr is earthed over contacts n3 andm3 if no digit has been dialled and the forced release is initiated. Ifa digit has been already dialled relay TP locks up over contacts tpl,c5, b4 and n3 as relay C is always operated prior to receipt of animpulse train and relay M locks up and the impulsing loop is opened atcontact m2 since relay H or DC will have been operated. A circuit is nowclosed from earth over contacts n3, b4, c5, m3 and wire fr to bringabout at the first code selector the release of the A digit selector andthe translating register if the latter is at the time in connection withit.

In the case of a call to a distant manual exchange, relay D is operatedwhen a junction to that exchange is seized. Should the caller nowrelease the connection the circuit over wire pu is opened and relays Aand B release. Earth is now extended over wire fr over contacts n3, b4and d2 and release of the A digit selector is brought about.

In the event of any switch failing to return to normal after use, relayCO or COC as the case may be remains operated and a lamp is flashed anda delayed alarm system set into operation. Also if it is desired to busyartificially the A digit selector or the translating register key KB orKBC is thrown thereby opening the test in circuit and causing asupervisory lamp to glow steadily. These alarm and supervisory lampcircuits are not shown as they are well known and are of no particularinterest in the carrying out of the invention.

We claim:

1. In a register sender, numerical registers for registering thenumerical digits of called subscribers telephone numbers, a plurality ofoice registers for registering the office code digits of the callednumbers, means responsive to a call for taking one of said numericalregisters into use and for connecting one of said office registers withsaid numerical register, a stepping switch associated with said officeregisters, registers in said ofce register operated responsive to thereceipt of the office code digits of a called number for marking saidstepping switch in accordance with the oice code digits received, saidstepping switch operated step-by-step in search of said marking, anoutput impulsing circuit associated with said numerical register, animpulsing device associated with said impulsing circuit operated in stepwith said stepping switch for interrupting said impulsing circuit,meanslfor transmitting a signal from said olice register in response tosaid switch finding said marking, and means responsive to said signalfor rendering further operation of said impulsing device ineffective tointerrupt said impulsing circuit.

2. In a register sender as claimed in claim l including a steppingswitch associated with said numerical register having a wiper includedin said impulsing circuit, and means for stepping said last switch insynchronism with the switch associated with the oflice register duringthe hunting operation for a marking.

3. In a register sender as claimed in claim l including aself-interrupting circuit for returning said stepping switch to itsnormal position effec.- tive in response to said switch finding amarking, and means responsive to said stepping switch reaching normalposition for transmitting a signal to prepare said impulsing circuit forfurther transmission.

4. In a register sender as claimed in claim 1 including aself-interrupting circuit for returning said stepping switch to itsnormal position effective in response to said switch finding a marking,and means responsive to said stepping switch reaching normal positionfor applying another of said office markings to said switch for thepurpose of transmitting another office digit.

5. In a register sender as claimed in claim l including an impulsereceiving relay associated with said numerical register for receivingthe incoming impulses, and means controlled by said relay for repeatingthe received impulses to set said cnice and numerical registers inaccordance therewith.

6. In a register sender as claimed in claim 1 including means associatedwith said numerical register for receiving the oce and numerical digitsof a called telephone number transmitte-d from a calling line, a switchassociated with said numerical register operated in accordance with thefirst transmitted oiice digit to select an idle oflice register in acorresponding group, a wiper on said last switch, and means forrepeating the remaining oice digits over said wiper to operate saidselected office register and for repeating the numerica-l digits tooperate the registers of said numerical register.

7. In a register sender as claimed in claim l including a switchassociated with said numerical register lor selecting an idle officeregister in accordance with the iirst received digit in the oiice code,and means effective in case said selecting switch is operated inaccordance with a particular rst digit for preventing the selection ofan cflice register and for effecting a translation independent of anofce register to transmit one or more routing digits.

8. In a register sender as claimed in claim 1 including a relayassociated with said numerical register, and means controlled by saidrelay for distributing the digits in the received call number to thecorresponding registers in the oice and numerical registers.

9. In a register sender as claimed in claim 1 including a rel-ayassociated with said numerical register, means controlled by said relayfor distributing the digits in the received called number to thecorresponding registers in the selected cice and numerical register, andmeans for operating said relay before the commencement of each digit andfor releasing said relay at the end of each digit.

10. In a register sender as claimed in claim 1 including an impulsereceiving relay for receiving the oflice and numerical digits dialled bya calling line, and means for repeating said digits over a wiper of theunits register of said numerical register to successively set saidregisters in accordance with the dialled digits.

11. In a register sender -as claimed in claim 1 including a wiper of theunits register in said numerical register, and means for operating saidWiper to distribute the dialled digits to the successive registers insaid oiiice and numerical registers.

12. In a register sender as claimed in claim 1 including means fortransmitting a signal from said ofce register to said numerical registerafter the transmission of said oice code by said cnice register, andmeans dependent upon the nature of said signal for determining whetherfurther digits are to be transmitted or whether said munerical registeris to be released.

13. In a register sender as claimed in claim 1 including an outputcontrol switch associated with said numerical register, means forstepping said control switch at the end of each transmitted digit, meansfor skipping the transmission of one or more cnice code digits, andmeans for automatically stepping said control switch for each cnice codedigit skipped in case the maximum number of o'ice code digits providedfor are not required.

14. In a register sender as claimed in claim l including a plurality ofoperating magnets for operating said oliice register, and a controlswitch associated with said office register sequentially connecting saidmagnets for operation.

15. In a register sender as claimed in claim 1 including a plurality cioperating magnets for operating said oiice register, a control switchassociated with said office register for sequentially connecting saidmagnets for operation, means for operating said control switch one stepafter receipt of each oice digit, and means for operating said controlswitch to apply said markings successively for said stepping switch inresponse to successive office code digit transmissions.

16. In a register sender as claimed in claim l including a controlswitch associated with said oilice register for successively applyingsaid markings for said stepping switch, and a stop relay for operatingsaid control switch in response to said stepping switch encountering amarking.

17. In a. register sender as claimed in claim l including a sendingswitch, a distributing frame and an output control switch associatedwith said numerical register, means for marking said sending switch oversaid distributing frame and the bank contacts of said control switch incase the rst digit received is a particular digit, means for operatingsaid sending switch to find said marking, means for transmitting a digitin accordance with said marking, and means for operating said controlswitch at the end of each transmitted digit to apply another marking tosaid sending switch.

18. In a register sender as claimed in claim 1 including a, relayassociated with said numerical register for initiating the steppingoperation of said stepping switch, and means for operating said relayafter the registers in the oiiice register have been set.

WILLIAM GEORGE PATTERSON. REGINALD GRIFFITH DIXON.

